Self-steering trucks

Abstract

A self-steering railway truck having interconnected steering arms associated with the axled wheelsets and having mechanism for yieldingly resisting yawing motion of the wheelsets including at least two devices, at least one of which provides a relatively high rate of increase of resistance per unit of deflection in the initial portion of the yaw motion and at least another of which provides a relatively low rate of increase of resistance per unit of deflection in a portion of the motion beyond the initial portion.

I claim: 
     
       1. A truck assembly for use with a railway vehicle on which the truck is adapted to be mounted, the truck assembly comprising two axle-borne wheelsets, load-bearing truck framing pivotally movable about a vertical axis with respect to the vehicle body, a steering arm for each wheelset movable with the wheelset with respect to the framing in the steering sense, each steering arm having load-bearing side portions with axle bearings movable with respect to the framing in the steering sense under the influence of yawing forces, each steering arm having a central portion movable with the side portions and extended from the side portions to a zone substantially midway between the axles of the wheelsets, the side and central portions of each steering arm being rigidly interconnected for conjoint movement in the yawing sense, pivot mechanism interconnecting the steering arms including a pivot joint in said zone interconnecting said central portions of the steering arms and providing a common upright axis for relative yaw motions of the steering arms independently of the load-bearing truck framing and enforcing coordinated substantially equal and opposite steering yaw motions of the wheelsets with respect to the load-bearing truck framing in either direction from a central position in which the wheelsets are parallel, and means for resiliently resisting steering yaw motions of the steering arms including first resilient means yieldingly reacting between the truck framing and at least one of the steering arms, and said means further including second resilient means reacting between the steering arms independently of the truck framing and yieldingly opposing said coordinated equal and opposite steering motions of the steering arms. 
     
     
       2. A truck assembly as defined in claim 1 in which said first resilient means comprises yieldingly resilient load-carrying pads between the framing and at least one of the associated steering arm. 
     
     
       3. A truck assembly for use with a railway vehicle on which the truck is adapted to be mounted, the truck assembly comprising two axle-borne wheelsets,   load-bearing truck framing pivotally movable about a vertical axis with respect to the vehicle body, a steering arm for each wheelset having load-bearing side portions with axle bearings movable with respect to the framing in the steering sense under the influence of yawing forces,   each steering arm having a central portion movable with the side portions and extended from the side portions to a zone substantially midway between the axles of the wheelsets, the side and central portions of each steering arm being rigidly interconnected for conjoint movement in the yawing sense,     pivot mechanism interconnecting the steering arms including a pivot joint in said zone interconnecting said central portions of the steering arms and providing a common upright axis for relative yaw motions of the steering arms independently of the load-bearing framing and enforcing coordinated substantially equal and opposite steering yaw motions of the wheelsets with respect to the truck framing in either yawing direction from a central position in which the wheelsets are parallel, and   motion control means for resiliently resisting yaw motions of the steering arms in either of said yawing directions from said central position including at least two elastomeric devices at least one of which provides a relatively high rate of increase of resistance per unit of deflection in the initial portion of the yaw motion of the steering arms and   at least another of which provides a relatively low rate of increase of resistance per unit of deflection in a portion of the motion beyond said initial portion,   the motion control mechanism providing for return of the steering arms to said central position in the absence of yawing forces.     
     
     
       4. A truck assembly as defined in claim 3 in which the motion control means for resiliently resisting yaw motions of the steering arms includes resilient pads interposed between the load-bearing truck framing and the load-bearing side portions of at least one of the steering arms. 
     
     
       5. A truck assembly as defined in claim 3 in which at least one of said elastomeric devices is arranged to react between the steering arms. 
     
     
       6. A truck assembly as defined in claim 3 in which both of said elastomeric devices are arranged to react between the steering arms.